Search

The pathogenesis of candidiasis involves invasion of host tissues by filamentous forms of the opportunistic yeast Candida albicans . Morphology-specific gene products may confer proinvasive properties. A hypha-specific surface protein, Hwp1, with similarities to mammalian small proline-rich proteins was shown to serve as a substrate for mammalian transglutaminases. Candida albicans strains lacking Hwp1 were unable to form stable attachments to human buccal epithelial cells and had a reduced capacity to cause systemic candidiasis in mice. This represents a paradigm for microbial adhesion that implicates essential host enzymes.

Mycobacterium haemophilum, a nontuberculous mycobacterium, is a pathogen in immunocompromised human patients. We report a case of M haemophilum-induced granuloma in the spinal cord of an American Bison ( Bison bison). M haemophilum infection was diagnosed by sequencing a portion of the 16 S ribosomal DNA and comparing the amplicon sequence with sequences in GenBank.

The objective of this study was to determine how fetal effects are altered when nicotine (N) and caffeine (CA) are administered concurrently at dosages that individually produce minimal effects to the fetus. Female ICR mice were bred overnight and were assigned to four groups: CA (125 mg/kg), N (12mg/kg), CA plus N (125 mg/kg plus 12 mg/kg, respectively) treated, and control (distilled water) groups. Dams were intubated with these dosages three times daily during gestational days (GD) 6-18 and were euthanized on GD 18. Live fetuses were sexed, weighed, and examined for external malformations. One-half of the fetuses were fixed in 10% formalin and examined for internal malformations using Wilson's method. The remaining half was fixed in 95% ethanol (ETOH), stained, and cleared (Inouye's method) for skeletal examinations. Ossification was assessed by staging and measuring craniofacial bones, and counting ossification centra in sternbrae and in cervical and sacrococcygeal vertebrae. Data were analyzed by analysis of variance (ANOVA) followed by Student-Newman-Keuls post-hoc tests set at p.05 significance level. The litter was used as the unit of measure and the ANOVA main effects were CA, N, and an interaction term (CA+N). In comparison to controls, CA treatment resulted in reduced bone measurements or reduced ossification scores in 5 of the 19 parameters examined, whereas for N only five parameters were significant. The main effects for interaction of CA+N were significant for seven parameters measured. Although it is difficult to assign the specific type of drug interaction that occurred because results were not completely consistent for all parameters measured, it may be concluded that in most parameters measured both CA and CA+N were different from controls, but CA was not different from CA+N. Under the experimental conditions of this study, we found that of the two drugs, caffeine had a significantly greater effect on fetal growth and ossification than nicotine.

Two distinct strain-related patterns of organism-host interaction on dorsal tongue of immunocompetent rats have been identified for Candida albicans: some isolates induce mucosal lesions, while other isolates penetrate the keratin layer but do not produce a lesion. This study examined the behavior of each of the two types of isolates in a cyclosporin-immunosuppressed rat model. Groups B (normal) and D (cyclosporin) were orally inoculated with a lesion-inducing isolate of C. albicans, while a non-lesional isolate was given to Groups A (normal) and C (cyclosporin). A typical dorsal tongue lesion developed in 4/18 rats in Group B and in 13/16 in Group D (P = 0.00267). No significant difference in infection rate between the normal and cyclosporin-treated animals was seen for the non-lesional isolate. The lack of a host inflammatory response associated with the non-lesional isolate may represent an ecologic advantage for the organism.

Saliva functions to protect the oral cavity from pathogenic invasion by modulating the ability of microbes to colonize the oral surfaces or limiting their growth and/or viability. Although the role of salivary secretions in the modulation of the oral bacteria flora has received considerable attention, little is known concerning its role in viral pathogenesis. Accordingly, the purpose of this study was to assess the effect of salivary secretions on herpes simplex virus type 1 (HSV-1) replication. Initially, HSV-1 plaque and titer reduction assays were performed to determine the ability of human submandibular/sublingual (HSMSL) and parotid (HPS) salivas to inhibit the early stages of HSV-1 infection (adsorption and penetration). Our results suggested that both HSMSL and HPS possess cell-protective and virus neutralization activities, with HSMSL being more active than HPS. Additional experiments were performed to determine the effect of saliva on the yield of virus progeny. Again, HSMSL caused a greater reduction of HSV-1 replication than did HPS. A similar effect could not be obtained using vaccinia, suggesting that this inhibitory activity of human saliva is selective. Collectively, these results suggest that human salivary secretions can modulate the replication of HSV-1 in vitro.